我是flex＆amp;的新手bison，我正在按照教程来帮助将用c编写的解析器转换为c ++。但是，在我按照本教程后，我的解析器不起作用。 从文件读取是好的，但从stdin读取会导致麻烦，按下ctrl D终止后，它会抛出错误，它会说语法错误。 这是我跟随的 picture of results showing syntax error
我搜索了很长时间，并尝试从#define yyterminate() return(token::END)中移除mc_lexer.l，正如其他人建议的那样，并没有成功。
我想这与eof令牌有关。但我现在不知道该怎么办。
这里是mc_parser.yy
%skeleton "lalr1.cc"
%require "3.0"
%debug
%defines
%define api.namespace {MC}
%define parser_class_name {MC_Parser}
%code requires{
namespace MC {
class MC_Driver;
class MC_Scanner;
}
// The following definitions is missing when %locations isn't used
# ifndef YY_NULLPTR
# if defined __cplusplus && 201103L <= __cplusplus
# define YY_NULLPTR nullptr
# else
# define YY_NULLPTR 0
# endif
# endif
}
%parse-param { MC_Scanner &scanner }
%parse-param { MC_Driver &driver }
%code{
#include <iostream>
#include <cstdlib>
#include <fstream>
/* include for all driver functions */
#include "mc_driver.hpp"
#undef yylex
#define yylex scanner.yylex
}
%define api.value.type variant
%define parse.assert
%token END 0 "end of file"
%token UPPER
%token LOWER
%token <std::string> WORD
%token NEWLINE
%token CHAR
%locations
%%
list_option : END | list END;
list
: item
| list item
;
item
: UPPER { driver.add_upper(); }
| LOWER { driver.add_lower(); }
| WORD { driver.add_word( $1 ); }
| NEWLINE { driver.add_newline(); }
| CHAR { driver.add_char(); }
;
%%
void
MC::MC_Parser::error( const location_type &l, const std::string &err_message )
{
std::cerr << "Error: " << err_message << " at " << l << "\n";
}
这里是mc_lexer.l
%{
/* C++ string header, for string ops below */
#include <string>
/* Implementation of yyFlexScanner */
#include "mc_scanner.hpp"
#undef YY_DECL
#define YY_DECL int MC::MC_Scanner::yylex( MC::MC_Parser::semantic_type * const lval, MC::MC_Parser::location_type *loc )
/* typedef to make the returns for the tokens shorter */
using token = MC::MC_Parser::token;
/* define yyterminate as this instead of NULL */
#define yyterminate() return( token::END )
/* msvc2010 requires that we exclude this header file. */
#define YY_NO_UNISTD_H
/* update location on matching */
#define YY_USER_ACTION loc->step(); loc->columns(yyleng);
%}
%option debug
%option nodefault
%option yyclass="MC::MC_Scanner"
%option noyywrap
%option c++
%%
%{ /** Code executed at the beginning of yylex **/
yylval = lval;
%}
[a-z] {
return( token::LOWER );
}
[A-Z] {
return( token::UPPER );
}
[a-zA-Z]+ {
yylval->build< std::string >( yytext );
return( token::WORD );
}
\n {
// Update line number
loc->lines();
return( token::NEWLINE );
}
. {
return( token::CHAR );
}
%%
mc_scanner.hpp
#ifndef __MCSCANNER_HPP__
#define __MCSCANNER_HPP__ 1
#if ! defined(yyFlexLexerOnce)
#include <FlexLexer.h>
#endif
#include "mc_parser.tab.hh"
#include "location.hh"
namespace MC{
class MC_Scanner : public yyFlexLexer{
public:
MC_Scanner(std::istream *in) : yyFlexLexer(in)
{
loc = new MC::MC_Parser::location_type();
};
//get rid of override virtual function warning
using FlexLexer::yylex;
virtual int yylex( MC::MC_Parser::semantic_type * const lval,
MC::MC_Parser::location_type *location );
// YY_DECL defined in mc_lexer.l
// Method body created by flex in mc_lexer.yy.cc
private:
/* yyval ptr */
MC::MC_Parser::semantic_type *yylval = nullptr;
/* location ptr */
MC::MC_Parser::location_type *loc = nullptr;
};
} /* end namespace MC */
#endif /* END __MCSCANNER_HPP__ */
mc_driver.cpp
#include <cctype>
#include <fstream>
#include <cassert>
#include "mc_driver.hpp"
MC::MC_Driver::~MC_Driver()
{
delete(scanner);
scanner = nullptr;
delete(parser);
parser = nullptr;
}
void
MC::MC_Driver::parse( const char * const filename )
{
assert( filename != nullptr );
std::ifstream in_file( filename );
if( ! in_file.good() )
{
exit( EXIT_FAILURE );
}
parse_helper( in_file );
return;
}
void
MC::MC_Driver::parse( std::istream &stream )
{
if( ! stream.good() && stream.eof() )
{
return;
}
//else
parse_helper( stream );
return;
}
void
MC::MC_Driver::parse_helper( std::istream &stream )
{
delete(scanner);
try
{
scanner = new MC::MC_Scanner( &stream );
}
catch( std::bad_alloc &ba )
{
std::cerr << "Failed to allocate scanner: (" <<
ba.what() << "), exiting!!\n";
exit( EXIT_FAILURE );
}
delete(parser);
try
{
parser = new MC::MC_Parser( (*scanner) /* scanner */,
(*this) /* driver */ );
}
catch( std::bad_alloc &ba )
{
std::cerr << "Failed to allocate parser: (" <<
ba.what() << "), exiting!!\n";
exit( EXIT_FAILURE );
}
const int accept( 0 );
if( parser->parse() != accept )
{
std::cerr << "Parse failed!!\n";
}
return;
}
void
MC::MC_Driver::add_upper()
{
uppercase++;
chars++;
words++;
}
void
MC::MC_Driver::add_lower()
{
lowercase++;
chars++;
words++;
}
void
MC::MC_Driver::add_word( const std::string &word )
{
words++;
chars += word.length();
for(const char &c : word ){
if( islower( c ) )
{
lowercase++;
}
else if ( isupper( c ) )
{
uppercase++;
}
}
}
void
MC::MC_Driver::add_newline()
{
lines++;
chars++;
}
void
MC::MC_Driver::add_char()
{
chars++;
}
std::ostream&
MC::MC_Driver::print( std::ostream &stream )
{
stream << red << "Results: " << norm << "\n";
stream << blue << "Uppercase: " << norm << uppercase << "\n";
stream << blue << "Lowercase: " << norm << lowercase << "\n";
stream << blue << "Lines: " << norm << lines << "\n";
stream << blue << "Words: " << norm << words << "\n";
stream << blue << "Characters: " << norm << chars << "\n";
return(stream);
}
这里是main.cpp
#include <iostream>
#include <cstdlib>
#include <cstring>
#include "mc_driver.hpp"
int
main( const int argc, const char **argv )
{
/** check for the right # of arguments **/
if( argc == 2 )
{
MC::MC_Driver driver;
/** example for piping input from terminal, i.e., using cat **/
if( std::strncmp( argv[ 1 ], "-o", 2 ) == 0 )
{
driver.parse( std::cin );
}
/** simple help menu **/
else if( std::strncmp( argv[ 1 ], "-h", 2 ) == 0 )
{
std::cout << "use -o for pipe to std::cin\n";
std::cout << "just give a filename to count from a file\n";
std::cout << "use -h to get this menu\n";
return( EXIT_SUCCESS );
}
/** example reading input from a file **/
else
{
std::cout << "2333333"<< std::endl;
/** assume file, prod code, use stat to check **/
driver.parse( argv[1] );
std::cout << "2333333"<< std::endl;
}
driver.print( std::cout ) << "\n";
}
else
{
/** exit with failure condition **/
return ( EXIT_FAILURE );
}
return( EXIT_SUCCESS );
}
这里是makefile
CC ?= clang
CXX ?= clang++
EXE = minisql
CDEBUG = -g -Wall
CXXDEBUG = -g -Wall
CSTD = -std=c99
CXXSTD = -std=c++11
CFLAGS = -Wno-deprecated-register -O0 $(CDEBUG) $(CSTD)
CXXFLAGS = -Wno-deprecated-register -O0 $(CXXDEBUG) $(CXXSTD)
CPPOBJ = main mc_driver
SOBJ = parser lexer
FILES = $(addsuffix .cpp, $(CPPOBJ))
OBJS = $(addsuffix .o, $(CPPOBJ))
CLEANLIST = $(addsuffix .o, $(OBJ)) $(OBJS) \
mc_parser.tab.cc mc_parser.tab.hh \
location.hh position.hh \
stack.hh mc_parser.output parser.o \
lexer.o mc_lexer.yy.cc $(EXE)\
.PHONY: all
all: wc
wc: $(FILES)
$(MAKE) $(SOBJ)
$(MAKE) $(OBJS)
$(CXX) $(CXXFLAGS) -o $(EXE) $(OBJS) parser.o lexer.o $(LIBS)
parser: mc_parser.yy
bison -d -v mc_parser.yy
$(CXX) $(CXXFLAGS) -c -o parser.o mc_parser.tab.cc
lexer: mc_lexer.l
flex --outfile=mc_lexer.yy.cc $<
$(CXX) $(CXXFLAGS) -c mc_lexer.yy.cc -o lexer.o
.PHONY: test
test:
cd test && ./test0.pl
.PHONY: clean
clean:
rm -rf $(CLEANLIST)
完整的代码可以在github下载